Household refrigerators generally utilize a simple vapor compression cycle for cooling air. Such a cycle includes a compressor, a condenser, an expansion device, and an evaporator connected in series and charged with a refrigerant. The evaporator is a type of heat exchanger which transfers heat from air passing over the evaporator to a refrigerant flowing through the evaporator, thereby causing the refrigerant to vaporize. The cooled air is used to refrigerate one or more refrigerator compartments.
A typical household side-by-side refrigerator includes a freezer storage compartment and a fresh food storage compartment arranged side-by-side and separated by a center mullion wall. Shelves and drawers typically are provided in the fresh food compartment, and shelves and wire baskets typically are provided in the freezer compartment. In addition, an ice maker may be provided in the freezer compartment. A freezer door and a fresh food door close the access openings to the freezer and fresh food compartments, respectively.
An evaporator chamber typically is located in the freezer compartment, and the evaporator chamber is substantially separated from the food storage portion of the freezer compartment by an evaporator chamber wall. The evaporator is located in the evaporator chamber, and a fan typically is located near an opening in an upper portion of the evaporator chamber wall. In operation, the fan draws air up through the evaporator chamber and injects cooled air into the food storage portion of the freezer compartment. The cooled air from the evaporator chamber also is supplied to the fresh food compartment by a duct which is located at the top rear portion of the fresh food compartment and is in air flow communication with the evaporator chamber.
In the past, and to control the temperature in the fresh food compartment, a manual damper was located in the duct in the fresh food compartment. By selecting a position for the damper, the amount of cool air passed from the freezer compartment into the fresh food compartment could be controlled. For example, as the damper was moved closer to a fully open position, more cooled air was passed into the fresh food compartment, and as the damper was moved closer to a fully closed position, less cooled air was passed into the fresh food compartment.
To improve temperature control, actuators have been included in side-by-side refrigerators to control the extent of air flow into the fresh food compartment. The actuator typically includes a thermo-mechanical or electric damper, and the actuator is located in an air duct in the fresh food compartment. The actuator is responsive to air temperature, and the amount of air flow allowed through the damper depends on the temperature at the actuator. Although such actuators provide acceptable air flow control, it is possible to improperly position the damper. Of course, improperly positioning the damper results in undesired warming or cooling of the fresh food compartment.